From: dblack@...
Date: 2002-12-15T23:57:29+09:00
Subject: Re: un-extending objects

Hi --

On Sun, 15 Dec 2002, ts wrote:

> a = A.new
> a.a
> a.stretch(M) { a.a }
> a.a
> pigeon%
>
> pigeon% b.rb
> a
> b
> b
> pigeon%

Do we consider that a bug or a feature? :-)

OK, the slightly less compact second iteration:

  class Object
    def stretch(mod)
      c = class << self; self; end
      before = methods
      cache = {}
      mod.instance_methods.select {|m| respond_to?(m)}.each do |m|
	alt = "__#{id}__#{m}"
	c.send(:alias_method,alt,m)
	cache[alt] = m
      end
      extend(mod)
      yield
      cache.each {|alt,m| c.send(:alias_method,m,alt)}
      (methods - before).each { |m| c.class_eval {undef_method(m)} }
    end
  end

I'd rather do this by binding and unbinding methods... but that technique
doesn't seem to fit exactly.

And there must be thread-related problems with this (aren't there
always? :-)


David

-- 
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav